The purpose of this proposal is twofold: (1) To study the myoelectric properties of the entire human colon, in health and in disease; (2) to investigate the myoelectric and motor properties of the feline ileocecal sphincter in vivo and to develop an in vitro whole organ preparation of this sphincter. Studies in man will be performed with a new electrode consisting of bipolar platinum rings which have been adapted directly from intracardiac recording electrodes. Myoelectric activity in the form of slow waves will be evaluated using computer analysis and the Fast-Fourier Transform. Spike potentials will be counted directly using a spike counter. Slow wave gradients will be mapped in the entire colon over 24-hr recording periods. Effect of meals, elemental diet will be assessed. Studies will be done in patients with diverticulosis, as well as severe chronic constipation. Patterns of colon excitation will be assessed in all colon segments and compared to the severity and distribution of the colonic diverticula. Additional studies in man will determine the mechanism of action of laxatives or anti-diarrheal agents on the colon. The effects of stress on colonic function will also be determined. Studies in the cat will be performed to evaluate the sphincteric properties of the ileocecal sphincter and how this sphincter functions to integrate the small and large intestine, and yet to functionally separate these areas. In vivo studies will evaluate the propagation of enterotoxin, bile salt or laxative induced migrating action potentials. Sphincteric function, myoelectric activity and induction of sphincteric reflexes will be studied in a perfused whole organ preparation of the ileum, ileocecal sphincter and colon. This grant is a continuation of an active 8-year program dealing with human colonic function and the physiological properties of the ileocecal sphincter, the entrance to the colon. Studies are extended to utilize a newly-designed ring electrode and objective computer assessment in man to evaluate total colonic myoelectric properties. Animal studies are extended to determine the integrative functions of the ileocecal sphincter.